To the Editor.—
Rutherford et al1 find that the revised national case definition of acquired immunodeficiency syndrome (AIDS) increased AIDS reporting in San Francisco by about 19%. Stehr-Green et al2 found a 22% increase in cases reported under the new definition for patients treated at six hemophilia centers. I have examined the data in the Centers for Disease Control weekly reports and calculated the percentage of cases reported since the definition change that would have been reported only under the new definition.
All cases of AIDS reported to the Centers for Disease Control using both the old and new definitions were recorded and the percentage of new cases that would have been reported solely under the new definition was calculated. The rate of increase at any time in the epidemic as a whole was calculated by averaging the number of new cases reported in the preceding five weeks